The disc rendering issue is probably related to the object normals. I'm not sure that they are 2-sided objects, which would explain it if they weren't.
The object primitives in TG2 are not meant to be extensive by any means. Where they serve the basic purposes of natural scene rendering they may be extended, but having a full suite of object primitives is most likely beyond the scope of what we'll be offering. An external modeling tool would handle those things much more effectively.
- Oshyan
